To make your workouts more productive, you can get a generator that you drive with the rear wheel of your bicycle when it is mounted in a stand. 

a. Your laptop charger uses 75 W. What is your body's metabolic power use while running the generator to power your laptop charger, given the typical efficiency for such tasks? Assume 100% efficiency for the generator. 

b. Your laptop takes 1 hour to recharge. If you run the genera- tor for 1 hour, how much energy does your body use? Express your result in joules and in Calories.